1. Field of the Invention
This invention relates generally to differential steering cross drive transmissions for track laying type vehicles and, more particularly, to a new and improved steer drive system for such transmissions.
2. Description of the Prior Art
Differential steering cross drive transmissions conventionally include planetary steer differentials or combining gear sets associated with each of the two output shafts of the transmission. Each steer differential has an output member drive connected to the corresponding output shaft, a drive input member drive connected to the transmission input through a range gearing section of the transmission, and a normally stationary reaction member. Each reaction member is drive connected to the transmission input through a steer drive system operative to hold each stationary and, for steering, to rotate each at equal, infinitely variable speeds up to a maximum speed but in opposite directions so that a speed difference is developed between the output members and between the output shafts. Such cross drive steering transmissions typically have multiple, parallel center lines about which various elements of the range gearing and steer drive system rotate and, consequently, housings which consume substantial quantities of valuable space within the vehicle. A steer drive system according to this invention permits single center line compactness in a differential steering cross drive transmission and, therefore, represents an improvement over heretofore known steer drive systems.